Print more info in MarkSweep::VerifyRoot

Refactored old root callback to use a new class called RootInfo.
RootInfo contains all the relevant info related to the root
associated with the callback. The MarkSweep::VerifyRoot function
now uses this info to print the StackVisitor's described location
if the GC root is of the type kRootJavaFrame.

Some other cleanup.

Example output:
E/art     (12167): Tried to mark 0x123 not contained by any spaces
E/art     (12167): Attempting see if it's a bad root
E/art     (12167): Found invalid root: 0x123 with type RootJavaFrame
E/art     (12167): Location=Visiting method
'void java.lang.Runtime.gc()' at dex PC 0xffffffff (native PC 0x0)
vreg=0

(cherry picked from commit 12f7423a2bb4bfab76700d84eb6d4338d211983a)

Bug: 18588862
Change-Id: Ic5a2781f704e931265ffb3621c2eab4b2e25f60f
diff --git a/runtime/throw_location.cc b/runtime/throw_location.cc
index 04abe64..4d2aec0 100644
--- a/runtime/throw_location.cc
+++ b/runtime/throw_location.cc
@@ -34,11 +34,11 @@
 
 void ThrowLocation::VisitRoots(RootCallback* visitor, void* arg) {
   if (this_object_ != nullptr) {
-    visitor(&this_object_, arg, 0, kRootVMInternal);
+    visitor(&this_object_, arg, RootInfo(kRootVMInternal));
     DCHECK(this_object_ != nullptr);
   }
   if (method_ != nullptr) {
-    visitor(reinterpret_cast<mirror::Object**>(&method_), arg, 0, kRootVMInternal);
+    visitor(reinterpret_cast<mirror::Object**>(&method_), arg, RootInfo(kRootVMInternal));
     DCHECK(method_ != nullptr);
   }
 }